The present invention relates to a defect substitution method of a disc-shaped recording medium having a sector structure, and to an apparatus for recording and reproducing data on a disc-shaped recording medium using said defect substitution method, and more specifically relates to an optical disc defect management method of an optical disc in a recording system in which error detection and correction coding spans a plurality of sectors, and to an optical disc recording and reproducing apparatus.
High speed random access is possible with disc-shaped recording media, and a high recording density can be achieved by formatting a disc with a narrow data track pitch and bit pitch. Disc-shaped recording media can be generally categorized based on differences in the applicable recording method as either a magnetic disc or optical disc, and can be further classified as either a fixed type or removable type media based on differences in the method whereby the medium is mounted in the recording/reproducing apparatus during use. The smallest recording unit of the physical recording area to which data is generally recorded on disc-shaped recording media is called a xe2x80x9csector.xe2x80x9d Sectors that cannot be used for data storage also occur in disc-shaped recording media as a result of defects during manufacture or damage occurring after manufacture. In addition to data writing errors occurring as a result of writing data sectors that are defective as a result of damage to the disc-shaped recording medium itself, data writing errors attributable to the operating environment can also occur as described below.
Optical discs, of which the DVD is typical, have been widely used in recent years as a large capacity recording medium because of their high recording density. Further advances in recording density have also been achieved to further increase storage capacity. Optical discs, however, are typically manufactured from low rigidity materials such as polycarbonate, and even disc deflection resulting from the dead weight of the disc cannot be ignored. In addition, this type of optical disc is commonly used as a replaceable, removable recording medium. For use, the disc is inserted into a recording and reproducing apparatus and mounted on a rotating spindle, and the positioning precision of the disc therefore cannot be assured.
It is also common to directly insert optical discs into the recording and reproducing apparatus without housing the disc in a protective case. Even when used housed in such a protective case, however, the entire recording medium is exposed during recording and reproducing because the protective case is not airtight. That is, optical disc recording media have essentially no shielding against the ambient environment. It should be noted that the problems specific to optical recording media reside in the point that these media are different from the hard disc recording media, including both low recording density fixed discs and removable hard discs, which are also a magnetic storage medium.
In addition to problems associated with their rigidity, mounting precision, and low airtightness, when an optical disc recording medium is inserted into a recorder and recorded or played, normal recording and reproducing can be inhibited by variations in the relative position to the optical pickup, or by foreign matter in the air interfering with the laser from the optical pickup. In such cases, data reading and writing can be obstructed through a wide band of the recording area, and burst mode recording and reproduction errors occur easily, as a result of the narrow track pitch and dot pitch enabling high density recording, even if there are no disc defects or damage to the information sector of the optical disc recording medium. While such burst-mode recording and reproducing problems occur easily in optical disc recording media, they are also found in the above-noted magnetic recording media and are common to all types of disc-shaped recording medium.
xe2x80x9cRecording defectxe2x80x9d is a general term for the inability to record as a result of a defect or damage to the recording medium itself or the conditions under which the disc is used. If a recording defect occurs when recording data to a particular sector, data is recorded continuously to the recording medium by saving the data to a reserved recording sector area, which is reserved separately from the normal data recording sectors, no matter what the cause of the recording defect. This operation of recording to a reserved sector area data that should be recorded to the sector in which a recording defect occurred is called xe2x80x9calternative recording,xe2x80x9d and the reserved sector area used for alternative recording is called an xe2x80x9calternative area.xe2x80x9d
In consideration for the above-noted problems, an object of the present invention is therefore to provide a defect management method whereby the size of the required alternative area can be suppressed and a disc-shaped recording medium can be efficiently used, and to provide a recording and reproducing apparatus for a disc-shaped recording medium.
A disc-shaped recording medium recording and reproducing apparatus for recording data by sector unit to a disc-shaped recording medium having a structure with a plurality of recording sectors, said disc-shaped recording medium recording and reproducing apparatus characterized by comprising: a coding means for error detection and correction coding said data twice, in row and column directions, and segmenting said data into sector units; a means for recording data coded in sector units to a sector in a first recording area of said disc-shaped recording medium; a defective sector discrimination means for reproducing said sector to discriminate whether the sector is a defective sector; and a defective sector substitution means for, when said sector is determined to be a defective sector, recording data recorded to a defective sector to an alternative sector in a second recording area disposed on said disc-shaped recording medium.